It has been long understood that a rifle's barrel changes shape and moves in multiple directions every time the rifle is fired. This effect is also found in shotgun and cannon barrels. In some instances, this movement of the barrel has been coined “barrel whip” and is when a weighted object (bullet) travels down the tubular barrel under intense gas pressure generally defined as when the barrel away from its “static” state. Barrel whip can occur when the bullet accelerates into a rapid spin, when the stock drops significantly so the muzzle rises when the rifle is fired, or when a pressure wave travels the length of the barrel. In the case of shotguns and unrifled cannon barrels, the “barrel whip” largely results from the pressure wave traveling along the barrel.
Barrel whip reduces the accuracy of the projectile expelled from the barrel and, therefore, the ability of a shooter to hit a target. Historically, manufacturers of barrels have simply accepted that the barrel's movement can't be eliminated. The remedy was to manufacture the barrel so that at least the movement was consistent with each shot. With a combination of cartridge loads and a consistently moving barrel whip, a rifle can be made more accurate by matching the load with the barrel. However, this requires that cartridge loads be customized to match each individual barrel and requires a high degree of customization.
Further, with each shot, the chamber can swell and produce an annular wave that travels between the muzzle and the breech. As the annular wave travels down the barrel, the bore diameter changes slightly as a result of the wave. If the bullet exits the barrel coincidentally with the wave at the muzzle, the bullet accuracy is greatly reduced since the bore and the bullet will be ejected through a bore that is made larger due to the wave. Traditional attempts to avoid this problem have been to change the cartridge load so that the bullet does not exit the barrel when the annular wave is at the muzzle. Again, this involves a high degree of customization and requires that cartridge loads match each individual barrel.
Further, as rounds are shot through a barrel, the barrel heats and the metal expands, becomes more flexible, and, therefore, the effect of barrel whip and any annular waves increases. Some tests have found that the center of the bore can change as much as 0.001 inches between the barrel temperatures of 77° F. (ambient) and 122° F. While the number of rounds that it takes to heat a barrel from ambient to over 120° F. varies greatly with the type for round, the type of barrel and other factors, such temperature changes can occur in as little as four or five rounds. Therefore, for multiple shots, the heat generated by the shots can adversely affect the accuracy of the barrel. This effect is exemplified in FIG. 4.
An additional problem arises in weapon systems that utilize gas return mechanisms to capture escaping gas from the barrel and redirect the gas into the action to cycle the bolt for filing the next round. Typically, a rifle with a gas management system, such as an AR15/M4 platform which includes a gas exit port disposed along the length of the barrel, and in some cases, is part of the front sight assembly. A metal tube is connected to the port and runs back along the length of the barrel and into the action of the rifle. As a bullet is fired down the barrel, gas is forced into the tube and then into the action to help cycle the bolt to fire the next round. In current designs, however, the gas return tube is free floating along the length of the barrel and only secured at its distal ends. A problem arises in that when gas is forced into the tube, it can cause the tube to flex and create additional harmonics that interact with the barrel whip described above. Thus, an additional loss of accuracy is suffered in these weapon systems.
Accordingly, it is an object of the present invention to provide a weapons system that was manufactured or modified to reduce the effects of barrel whip, annular or pressure waves, and heat produced when firing.
It is a further object of the present invention to provide a gas management system for a weapon system that reduces flex and harmonics associated with a gas return tube to improve accuracy while maintaining the benefits of a gas management system.
It is a further object of the present invention to provide a control mechanism to adjust the flow of gas return to the action.